Odd cache behavior

[Jim Ohlstein]

Igor Sysoev wrote:
> On Fri, Oct 02, 2009 at 01:07:24PM -0400, Jim Ohlstein wrote:
> 
>> Hello,
>>
>> I'm seeing odd disk usage statistics for my cache. The cache is 
>> primarily of small files (images, javascript, and css) and sits on a 
>> 128GB SSD using ext2 file system mounted with "noatime" option. The 
>> cache is all that the the drive is being used for at this time.
>>
>> The attached graphs were generated by Munin using df. The data from du 
>> correlates closely with df when run manually.
>>
>> As you can see, periodically, with no set interval, disk usage rises 
>> gradually, and then drops precipitously. I don't see anything out of the 
>> ordinary in the error log. The cache serves about 2.8-3 million requests 
>> per day, up from ~2.2-2.4 million one month ago.
>>
>> The cache config is:
>>
>> fastcgi_cache_path /falcon/cache levels=1:2 keys_zone=one:1024m 
>> inactive=1d max_size=80g;
>>
>> where the SSD is mounted as /falcon.
> 
> As I understand /falcon is used solely for nginx cache ?

This is correct.

> Could you monitor inode usage also ?

See attached graphs.

> Did you restart nginx in the times of the drops or not ?

No.

> Currently I have no idea why it may be.
> 
> 


-- 
Jim Ohlstein
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